This page presents some ideas for expressing NDVI in terms of population density for the City of Denver, Colorado.

1 Population density

A map of population density by block group per 2016-2020 American Community Survey 5-year Estimates

Population density tertiles

2 NDVI

A map of NDVI of each block group. Note NDVI is measured using Landsat-8 at a spatial resolution of 30 meters squared on July 4, 2021, a cloud-free day. The weighted average NDVI of each block group excludes bodies of water.

NDVI tertiles, overall

3 Explore relationship between population density, NDVI, and equity indices

3.1 Scatterplot of population density x NDVI

3.2 Map of NDVI tertiles within tertiles of population density

3.3 Scatterplot of equity index (CDPHE definition) x NDVI x pop. density tertile

3.4 Scatterplot of equity index (Denver definition) x NDVI

3.5 Scatterplot of equity index (CDPHE definition) x pop. density

4 Possible composite measures considering both population density and NDVI

  1. Population density per NDVI (population density per square mile / NDVI)
  2. A ranking of population density per NDVI
  3. Quantiles within quantiles as above.

The first is somewhat difficult to visualize on a map because the distribution has a right skew with some very high values and most much lower.

##     Min.  1st Qu.   Median     Mean  3rd Qu.     Max.     NA's 
##    457.5  14482.2  22057.3  35548.7  36465.0 364573.0        8

The second is easier to visualize because the distribution is uniform by definition (a simple rank).

##    Min. 1st Qu.  Median    Mean 3rd Qu.    Max.    NA's 
##     1.0   131.5   262.0   262.0   392.5   523.0       8

Map population density per NDVI and the ranking of population density per NDVI on the same map.



Copyright © 2022 Michael D. Garber